It's not really the themes that are different between these filmmakers as their voices and directing styles.

If you see 5 scenes, each by a different writer/director (Anderson, Smith, Baumbach, Allen, and Ephron, for example), you'd be able to tell what scene belonged to who, even if the subject matter and actors were exactly the same. It's the delivery of the message that differs, not the message itself.

Plus, like I said, I thought the nature of the dad's terminal illness and the way it was handled made this more than your typical "Life sucks, but it's better than death" film.